<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>const</title>
</head>
<body>
  <script>
    const pi = 3.14
    const e = 1.414
    console.log(pi,e)
    // pi = 1.1 // error

    const o = {name: 'jack', age: 30}
    // o = {} // error
    o.name = 'rose' // ok

    //
    let _val = 10
    let $store = {}
    let $emit = {}
    let $on, $off, $remove

  </script>
</body>
</html>